We debated for some time the best way to attach the roof to the building.  Originally, we planned to build the entire roof on the ground, and then lift it into place.  I decided this would be difficult due to the weight.  Then we had the idea of building just enough of the truss frame to lift into place and sit on top of the walls.  Too unsteady, and still too heavy.  After further discussion, we hit upon the idea of placing the trusses on top of the observatory and securely (but temporarily) attaching them to the walls.  After this was accomplished, the two trusses were securely spanned with 2x4's.  These supports will give us something to attach the roofing to.  Next, we will unsecure the roof frame from the walls, jack each side up one at a time and attach the roller mechanisms underneath.